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Optical Switching of a Quantum Cascade Laser in Continuous Wave Operation

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Chinese Physics Letters 2010年第1期27卷 268-270页

作者： Gang Chen Seong-wook park i-Chun A. Chen Clyde G. Bethea Rainer Martini Department of Physics and Engineering Physics Stevens Institute of Technology Castle Point on Hudson Hoboken N3 07030 USA College of Optoelectronic Engineering Chongqing University Chongqing 400044

We demonstrate an optical switching in a middle infrared continuous-wave quantum cascade laser operated in single mode by illuminating its front facet with a near infrared laser. A decrease in the laser net gain is observed in the amplified spontaneous emission spectrum. This is attributed to an increase of the carrier concentration caused by the near infrared excitation. The net gain reduction allows the quantum cascade laser to be completely switched off from single mode lasing. This optical switching can be used to convert near infrared signals into middle infrared signals for free space communication.

关键词： Chinese climate network complex systems small world community

Efficient thermal management and all-season energy harvesting using adaptive radiative cooling and a thermoelectric power generator

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Journal of Energy Chemistry 2023年第9期84卷 496-501页

作者： Chanil park Woohwa Lee Choyeon park Sungmin park Jaeho Lee Yong Seok kim Youngjae Yoo Advanced Materials Division Korea Research Institute of Chemical Technology(KRICT)Daejeon 34114Republic of Korea Department of Mechanical and Aerospace Engineering University of CaliforniaIrvineCA 92617United States Department of Advanced Materials Engineering Chung-Ang UniversityAnseong 17546Republic of Korea

Passive daytime radiative cooling(PDRC) is useful for thermal management because it allows an object to emit terrestrial heat into space without the use of additional *** produce sub-ambient temperatures under direct sunlight,PDRC materials are designed to reduce their absorption of solar energy and to enhance their long-wavelength infrared(LWiR) *** recent years,many photonic structures and polymer composites have been studied to improve the cooling system of ***,in cold weather(i.e. during winter in cold climates),buildings need to be kept warm rather than cooled due to heat *** overcome this limitation,temperature-responsive radiative cooling is a promising *** the present study,adaptive radiative cooling(ARC) film fabricated from a polydimethylsiloxane/hollow SiO_(2) microsphere/thermochromic pigment composite was *** found that the ARC film absorbed solar radiation under cold conditions while exhibiting radiative cooling at ambient temperatures above 40℃.Thus,in outdoor experiments,the ARC film achieved sub-ambient temperatures and had a theoretical cooling power of 63.2 W/m~2 in hot *** also demonstrated that radiative cooling with an energy harvesting system could be used to improve the energy management of buildings,with the thermoelectric module continuously generating output power using the ARC ***,we believe that our proposed ARC film can be employed for efficient thermal management of buildings and all-season energy harvesting in the near future.

关键词： Thermal management Daytime radiative cooling Temperature-adaptive film Thermoelectric device Energy harvesting

Stress analysis model of strip winding system with a sleeve for a coil of thin stainless steel

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Journal of iron and Steel Research international 2017年第1期24卷 1-7页

作者： Yong-hui park kyutae park Sung-yeun Won Wan-kee Hong Hyun-chul park Graduate School of Engineering Masterships Pohang University of Science and Technology(POSTECH)Kyungbuk 790 784PohangRepublic of Korea Mechanical Engineering Pohang University of Science and Technology(POSTECH)Kyungbuk 790-784PohangRepublic of Korea Mechanical Facility Research Group Engineering Solution CenterPOSCOKyungbuk 790-360PohangRepublic of Korea

in a strip winding process,the sleeve is a hollow cylinder that is mounted between a strip coil and a mandrel to maintain uniform coil shape when the strip coil is very thin,but its deformation behavior has not been investigated ***,a finite element（FE）model was presented to calculate the stress distribution in a sleeve and strip coil when 1-3mm-thick stainless steel was wound around the *** FE model was developed by extending aprevious model by adding a sleeve between the mandrel and strip,and by modifying the boundary and interaction *** strip winding process was divided into an initial process and a steady-state *** the initial process,the minimum and maximum pressure required on the belt wrapper to maintain coil shape by self-friction of the strip was calculated by the FE model when the belt wrapper is ejected at the end of the initial *** the initial process,an analytical model of the steady-state process was established to calculate the stress distribution and was compared with the FE model to validate *** suggested analytical model took 11 sto give the same stress distribution that the FE model took 30 dto produce.

关键词： Strip winding system Belt wrapper Grooved joint Radial stress Hoop stress Von-Mises stress interference fit

System lifecycle processes for cyber security in a research reactor facility

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Science China(information Sciences) 2014年第7期57卷 247-258页

作者： park Jaekwan park JeYun kiM Youngki korea Atomic Energy Research institute Daedeok-daero 989-111Dukjin-dongYuseong-guDaejeonKorea

The digitalization of nuclear facilities has brought many benefits,including high performance and convenient maintainability,in terms of facility ***,cyber accidents accompanied by the use of digital technologies have increased,and cyber security has been one of the most important issues in the nuclear industry *** guidelines have been published for nuclear power plants,but it is difficult to apply all requirements within the guidelines to research reactor facilities because the characteristics in terms of facility scale,purpose,and system design,are different from those of power *** address this emerging topic,this paper introduces system lifecycle processes for cyber security in a research reactor *** addresses the integration of activities for securing systems and guarding a facility safely using the practices at a research reactor facility.

关键词： software project management computer-based safety systems cyber security security program

Development of a cloud condensation nuclei(CCN)counter using a laser and charge-coupled device(CCD)camera

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Frontiers of Environmental Science & Engineering 2011年第3期5卷 313-319页

作者： Mikyung park Jinkwan OH kihong park School of Environmental Science and Engineering Gwangju Institute of Science and TechnologyGwangju 500-712The Republic of Korea

A continuous flow streamwise thermal gradientcloud condensation nuclei(CCN)counter with anaerosol focusing and a laser-charge-coupled device(CCD)camera detector system was developed *** countingperformance of the laser-CCD camera detector system wasevaluated by comparing its measured number concentrationswith those measured with a condensation particlecounter(CPC)using polystyrene latex(PSL)and NaClparticles of varying *** CCD camera parameters(***,gain,gamma,and exposure time)wereoptimized to detect moving particles in the sensing volumeand to provide the best image to count *** CCNcounter worked well in the particle number concentrationrange of 0.6-8000#·cm^(-3)and the minimum detectablesize was found to be 0.5μ*** supersaturation in theCCN counter with varying temperature difference wasdetermined by using size-selected sodium chloride particlesbased on köhler *** developed CCNcounter was applied to investigate CCN activity ofatmospheric ultrafine particles at 0.5%*** showed that CCN activity increased with increasingparticle size and that the higher CCN activation forultrafine particles occurred in the afternoon,suggesting thesignificant existence of hygroscopic or soluble species inphotochemically-produced ultrafine particles.

关键词： aerosol cloud condensation nuclei(CCN)counter ultrafine particle

GENERAL DECAY FOR A QUASiLiNEAR SYSTEM OF ViSCOELASTiC EQUATiONS WiTH NONLiNEAR DAMPiNG

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Acta Mathematica Scientia 2012年第4期32卷 1321-1332页

作者： Jong Yeoul park Sun Hye park Department of Mathematics Pusan National UniversityBusan 609-735 South Korea

in this paper, we consider a system of coupled quasilinear viscoelastic equa- tions with nonlinear damping. We use the perturbed energy method to show the general decay rate estimates of energy of solutions, which extends some existing results concerning a general decay for a single equation to the case of system, and a nonlinear system of viscoelastic wave equations to a quasilinear system.

关键词： general decay coupled quasilinear equations viscoelastic equations perturbed energy method

Empathic Responses of Behavioral-Synchronization in Human-Agent interaction

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Computers, Materials & Continua 2022年第5期71卷 3761-3784页

作者： Sung park Seongeon park Mincheol Whang Savannah College of Art and Design SavannahGA31401USA Sangmyung University Seoul03016Korea

Artificial entities,such as virtual agents,have become more *** long-term presence among humans requires the virtual agent’s ability to express appropriate emotions to elicit the necessary empathy from the *** empathy involves behavioral mimicry,a synchronized co-movement between dyadic ***,the characteristics of such synchrony between humans and virtual agents remain unclear in empathic *** study evaluates the participant’s behavioral synchronization when a virtual agent exhibits an emotional expression congruent with the emotional context through facial expressions,behavioral gestures,and *** viewed an emotion-eliciting video stimulus(negative or positive)with a virtual *** participants then conversed with the virtual agent about the video,such as how the participant felt about the *** virtual agent expressed emotions congruent with the video or neutral emotion during the *** participants’facial expressions,such as the facial expressive intensity and facial muscle movement,were measured during the dialog using a *** results showed the participants’significant behavioral synchronization(i.e.,cosine similarity≥.05)in both the negative and positive emotion conditions,evident in the participant’s facial mimicry with the virtual ***,the participants’facial expressions,both movement and intensity,were significantly stronger in the emotional virtual agent than in the neutral virtual *** particular,we found that the facial muscle intensity of AU45(Blink)is an effective index to assess the participant’s synchronization that differs by the individual’s empathic capability(low,mid,high).Based on the results,we suggest an appraisal criterion to provide empirical conditions to validate empathic interaction based on the facial expression measures.

关键词： Facial emotion recognition facial expression virtual agent virtual human embodied conversational agent empathy human-computer interaction

Use of drilling performance to improve rock-breakage efficiencies:A part of mine-to-mill optimization studies in a hard-rock mine

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international Journal of Mining Science and Technology 2020年第2期30卷 179-188页

作者： Junhyeok park kwangmin kim Department of Mining and Geological Engineering University of ArizonaTucsonAZ 85721USA

in a hard-rock mine,blasting is an important rock-breakage process that impacts energy consumption both in downstream comminution processes and mine *** the blast fragmentation to improve rock-breakage efficiencies during crushing and grinding is key to mine-to-mill(MTM)*** study explores the use of monitoring while drilling(MWD)data to achieve this *** penetration rates(PRs)were extracted from blastholes to estimate intact rock properties and predict the breakage efficiencies that directly affect comminution energy *** intact rock properties,tensile strength(TS)and Bond work index(BWi),were correlated with the PR data to predict these efficiencies in crushing and grinding,*** of the complexity of the raw MWD data and effects of various disturbances,the MWD data was preprocessed and normalized to achieve a representative PR value at each *** preprocessing entailed defining valid PR ranges from the MWD data that could eliminate the noise related to discontinuity features in the rock mass structure as well as errors in operator *** PR data was also normalized using the adjusted penetration rate(APR)to minimize the effects of mechanical factors such as drill feed force,torque,and rotational *** correlate the representative APR value with intact rock properties,TS and BWi,various laboratory experiments were conducted:drilling tests using a high-precision coring machine,Brazilian disc tests,and Bond grindability *** on the results of these experiments,models were developed to predict rock-breakage efficiencies during crushing and grinding based on *** result of this study can be used to obtain blast energy designs that consider comminution energy consumption and efficiency in the downstream rock-breakage processes.

关键词： Monitoring while drilling(MWD) Mine-to-mill(MTM)optimization Rock-breakage efficiency Drilling penetration rates

An investigation on Open-RAN Specifications:Use Cases,Security Threats,Requirements,Discussions

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 13-41页

作者： Heejae park Tri-HaiNguyen Laihyuk park Department of Computer Science and Engineering Seoul National University of Science and TechnologySeoul01811Republic of Korea Faculty of information Technology School of TechnologyVan Lang UniversityHo Chi Minh City70000Vietnam

The emergence of various technologies such as terahertz communications,Reconfigurable intelligent Surfaces(RiS),and Ai-powered communication services will burden network operators with rising infrastructure ***,the Open Radio Access Network(O-RAN)has been introduced as a solution for growing financial and operational burdens in Beyond 5G(B5G)and 6G networks.O-RAN promotes openness and intelligence to overcome the limitations of traditional *** disaggregating conventional Base Band Units(BBUs)into O-RAN Distributed Units(O-DU)and O-RAN Centralized Units(O-CU),O-RAN offers greater flexibility for upgrades and network ***,this openness introduces new security challenges compared to traditional *** existing studies overlook these security requirements of the O-RAN *** gain deeper insights into the O-RAN system and security,this paper first provides an overview of the general O-RAN architecture and its diverse use cases relevant to B5G and 6G *** then delve into specifications of O-RAN security threats and requirements,aiming to mitigate security vulnerabilities *** providing a comprehensive understanding of O-RAN architecture,use cases,and security considerations,thisworkserves as a valuable resource for future research in O-RAN and its security.

关键词： O-RAN architecture use cases security issues security requirements security discussions